Vacuum plant located in pre-vacuum tank



Nov. 27, 1956 H. SONNBERGER VACUUM PLANT LOCATED IN PRE-VACUUM TANK Filed Jan. 4, 1952 1N VENTOR United States Patent VACUUM PLANT LOCATED IN PRE-VACUUM TANK Heinrich Sonnberger, Heidenheim (Brenz), Germany, assignor to Carl Zeiss, Heidenheim (Brenz), Germany Application January 4, 1952, Serial No. 264,997

2 Claims. (Cl. 230232) In the usual type of vacuum plant, a partial vacuum is first formed in a preliminary-vacuum tank by means of an ordinary pump, and the desired high vacuum is then produced by further exhausting with the vacuum pump proper. Because of the troublesome noises caused by the pre-exhausting pump, it has hitherto been customary to set up this pump separately from the remaining plant components, frequently even in another room.

This separation, however, is very undesirable in many cases and is especially so in the construction of small and handy instruments working with a high vacuum, as for instance electronic microscopes. Direct connection in such cases has so far been impracticable because of interference with operation from the attendant racket. This difficulty is overcome by the present invention, in which the pre-exhausting pump is disposed within the pre-vacuum tank. Since sound is preponderantly transmitted through air, this arangement gives very effective damping, and therewith abatement of the objectionable pump noises.

Any such means as have so far been used for minimizing vibration and clatter, can be employed without difliculty also in the interior of the pre-vacuum tank. In particular, the electric motor for driving the pre-exhausting pump can be accommodated inside this tank. It is merely necessary, since the motor cannot be cooled by ventilation, to provide for suflicient cooling by radiation. Inasmuch as outwardly, the pre-vacuum tank may be of any desired form, there is nothing to prevent adapting its design to the parts to be built into the tank or combining these parts into a unit. The manner in which the pre-vacuum tank is combined with the remaining parts of the plant will depend upon the special requirements of "ice each particular case and may vary within wide limits. As an instance, the pre-vacuum tank may be in the form of a seat for the person operating the instrument.

The drawing shows the invention in a schematic plan sketch: Disposed in a cylindrical and completely closed vessel a representing the pre-vacuum tank is a base plate b, which is suspended from the wall of tank a by springs c. Mounted on base plate b are a pre-exhausting pump d and an electric motor e for driving it. The pump exhausts the air in the tank through an inlet d2 of the pump. From pump d, a hose d1 sealed against the pre-vacuum leads through the wall of tank a into the outer air through which the exhausted air will be put out. While, in a pump set up in the usual Way, the pertinent shut-0E valve is located at the suction end, this valve must here be imagined as being at the pressure end. As long as the pump is working, a vacuum prevails in the interior of the tank, so that the noises occasioned by the pump cannot escape outside.

I claim:

1. In a vacuum plant of an electron microscope a hermetic pre-vacuum tank, means for exhausting said tank, said means being a pre-exhausting pump with an inlet in the interior of said tank and an outlet outside of said tank, as well as a motor coupled with said preexhausting pump, said pre-exhausting pump being suspended in the interior of said pre-vacuum tank for re-.

ducing the noise of said pump it being in operation.

2. In a vacuum plant of an electron microscope a hermetic pre-vacuum tank, means for exhausting said tank, said means being a pre-exhausting pump with an inlet in the interior of said tank and an outlet outside of said I tank, as well as an electric motor coupled with said pre-exhausting pump, said electric motor and said we References Cited in the file of this patent UNITED STATES PATENTS 2,028,985 Mahon Jan. 28, 1936 2,060,980 Ell Mar. 17, 1936 2,364,038 Touborg Nov. 28, 1944 2,510,632 Hemphill June 6, 1950 

